storage: lvm: Separate creating of the volume from building

Separate the steps to create libvirt's volume metadata from the actual
volume building process. This is already done for regular file based
pools to allow job support for storage APIs.

src/storage/storage_backend_logical.c

@@ -702,32 +702,16 @@ cleanup:
 
 
 static int
-virStorageBackendLogicalCreateVol(virConnectPtr conn,
-                                  virStoragePoolObjPtr pool,
-                                  virStorageVolDefPtr vol)
+virStorageBackendLogicalBuildVol(virConnectPtr conn,
+                                 virStoragePoolObjPtr pool,
+                                 virStorageVolDefPtr vol,
+                                 unsigned int flags)
 {
     int fd = -1;
     virCommandPtr cmd = NULL;
     virErrorPtr err;
 
-    if (vol->target.encryption != NULL) {
-        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
-                       "%s", _("storage pool does not support encrypted "
-                               "volumes"));
-        return -1;
-    }
-
-    vol->type = VIR_STORAGE_VOL_BLOCK;
-
-    if (vol->target.path != NULL) {
-        /* A target path passed to CreateVol has no meaning */
-        VIR_FREE(vol->target.path);
-    }
-
-    if (virAsprintf(&vol->target.path, "%s/%s",
-                    pool->def->target.path,
-                    vol->name) == -1)
-        return -1;
+    virCheckFlags(0, -1);
 
     cmd = virCommandNewArgList(LVCREATE,
                                "--name", vol->name,
@@ -786,7 +770,7 @@ virStorageBackendLogicalCreateVol(virConnectPtr conn,
 
     return 0;
 
- error:
+error:
     err = virSaveLastError();
     VIR_FORCE_CLOSE(fd);
     virStorageBackendLogicalDeleteVol(conn, pool, vol, 0);
@@ -796,6 +780,36 @@ virStorageBackendLogicalCreateVol(virConnectPtr conn,
     return -1;
 }
 
+
+static int
+virStorageBackendLogicalCreateVol(virConnectPtr conn ATTRIBUTE_UNUSED,
+                                  virStoragePoolObjPtr pool,
+                                  virStorageVolDefPtr vol)
+{
+    if (vol->target.encryption != NULL) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("storage pool does not support encrypted volumes"));
+        return -1;
+    }
+
+    vol->type = VIR_STORAGE_VOL_BLOCK;
+
+    VIR_FREE(vol->target.path);
+    if (virAsprintf(&vol->target.path, "%s/%s",
+                    pool->def->target.path,
+                    vol->name) == -1)
+        return -1;
+
+    if (virFileExists(vol->target.path)) {
+        virReportError(VIR_ERR_OPERATION_INVALID,
+                       _("volume target path '%s' already exists"),
+                       vol->target.path);
+        return -1;
+    }
+
+    return 0;
+}
+
 static int
 virStorageBackendLogicalBuildVolFrom(virConnectPtr conn,
                                      virStoragePoolObjPtr pool,
@@ -823,7 +837,7 @@ virStorageBackend virStorageBackendLogical = {
     .refreshPool = virStorageBackendLogicalRefreshPool,
     .stopPool = virStorageBackendLogicalStopPool,
     .deletePool = virStorageBackendLogicalDeletePool,
-    .buildVol = NULL,
+    .buildVol = virStorageBackendLogicalBuildVol,
     .buildVolFrom = virStorageBackendLogicalBuildVolFrom,
     .createVol = virStorageBackendLogicalCreateVol,
     .deleteVol = virStorageBackendLogicalDeleteVol,